People do that crap to me every once in awhile in my tC...every now and then I'll tap my foot on the brake just enough to make my brake lights come on but not enough to really slow down (obviously my foot is still on the gas) and watch then back off...or i'll just let off the throttle a bit and slow down..especially if they have plenty of room to go around me...
probably not the smartest things for me to do but then again I'm not the smartest person on the road